Unlockable safety lock



FeB. 4, 1930. LEWIS 7 1,745,495

UNLOCKABLE SAFETY LOCK Filed Jan. 18. 192

Patented Feb. 4, 1930 V-UNITED'STATES PATENT OFFICE,

THEODORE B. LEWIS, OF NEW YORK, N. Y., ASSIGNOR TO SECURITY SEAL & LOCK CORP. OF NEW YORK, N. Y., A CORPORATION OF NEW YORK UNIOCKABLE SAFETY LOCK Application filed January 18, 1927." Serial No. 161,748.

This invention relates to unlockable safety-locks for containers and particularly for containers such as envelopes which are made of paper or like material.

Money and documents are often stored or placed in the mails inside of containers and it is of prime importance to know whether the contents of a container have been accessible to anyone during the time that it was out of a principals hands. Consequently, several fastening devices or looks have been devised for use on envelopes or other containers and which are intended tobe free from unauthorized tampering and unlockable without such alteration or destruction of the lock as would make known the fact that some one had meddled with the. container or with its contents. It is known that many of the so-calledsafety-locks are capable of performing their useful functions only as against the ordinaryability of man and that a person skilledin the construction and operation of such locks and having criminal cunning with the assistance of wires or of thin blades of steel can open such locks by as to. make it possible to place its locking element Well within the sheath and away from the opening of the sheath. The sheath I is so conformed as to snugly accommodate theblade element of a'second section of the I I safety-lock, the constructionof the sheath section being characterized by its thinness and'by the fact that the under surface of'the sheath directly contacts the paper or flexi- .ble material of the envelope so that the additional effort of the paper assists in maintainingithe outline or edgesof the spring or'locking element of the sheath within the sheath and out of range of any tool or blade no matter how introduced.

Further and other objects are set forth hereinafter together withdetails of the invention which are described and illustrated. The drawings illustrate one embodiment of the invention, in which:

Fig. 1 is a plan view of the safety-lock.

Fig. 2 is a view from the under side of the safety-lock illustrated in Fig. 1'.

Fig. 3 is a section online 3+3 of Fig-1 .with the sheath section member in engage inept with a sheet of paper or flexible materia Fig. 4 is a side elevationof the safety-lock.

Referring now particularly to the drawings, the safety-lock comprises two individual sections; a sheath section 10 and a blade element section 11, both ofwhich are illustrated in an engaged relation, and in adisengaged relation in Fig. 4. As disclosed, the sheath section 10 is made up of a single piece Of sheet metal having two major portions, an upper lap 12 and an under lap 13 connected togetherat one edge of the section by a fold 14. For ordinary purposes, this fold may be along either of the two side edges of the sheath section 10 but I have found that it is desirableto have the fold at the rear edge of the sheath section as illustrated. The upper lap 12 has a raised central portion 15 which has a clear or open space of a height preferably a little greater'than the thickness of the sheet metal used. The under surface of the portion of the upper lap outside ofthe area of the central portion 15 is maintained in contact with the opposite portion of the upper surface of the lower lap by a plurality of lugs 16, 17 which extend from the upper lap 12 and are adapted to be bent over the under surface of the under lap 13 in the'mam ner illustrated in Fig. 2. Lugs 16' comprise a pair of lugs near to the rear edge 14 of the sheath section, and lugs 17 comprise a pair of lugshaving such length and position'as to perform desired functions which will bere-' ferred to hereinafter.

A spring locking element 18 is cut out of the under lap 13 in such a manner as to be disposed opposite the raised central portion 15 of the upper lap 12, the spring locking element having its free and engaging end extending toward, and near to, the rear end 14 of the sheathsection. This spring locking element is biased upwardly, as illustrated in Fig. 3, and the locking end may come into contact with the under surface of the upper lap 12. In order to assist in the spring action of locking element 18 as well as to maintam all portions thereof above the plane of the under surface of the under lap 13, lugs 17 are extended over a portion of the edges of the locking element. The spring portion of locking element 18 preferably starts just to the rear of the rear edges of these lugs. Accordingly, there cannot be any edge of the locking element above which a blade of metal could be inserted,'no matter how thin the blade might be. i

The blade element 19 of the blade element section 11 is intended to enter the clear or open space formed by the raised central portion 15 opposite the forward edge 20 of the under lap. 13. The position of this forward edge 20 is illustrated, in the present embodiment, as finishing to the rear of the forward edge 21 of the upper lap 12 and, if the two laps are finished off at approximately the' same lengths, it would not be necessarily desirable to providean opening or slot 22 in the upper lap 12. This slot is desirable,fliowever, for it permits the forward edge 21 of the upper lap 12 to be offset so as to lie below the blade element 19 when the two sections are in engagement, F ig. 3. This construction provides a snug locking relation which contributes tothe value of the safety-lock in that the only Opening or entrance to the clear or open space below the raised portion 15 is of aminimum size and has close-fitting edges.

In addition to the advantage just referred to, the open space is designed so as to have the long measurement extending from the slot 22 to the rear edge of the sheath section 10.

Such a design enables the locking elements of the twosections to be pla-ced well out of reach and away from the forward end of the sheath section. The blade element 19 has a lip 23 extending below the under surface of the bladeelement. .It is desirable that the forward edge of this lip be ata distance, from shoulders 24, 24of the blade element section 11, which is but slightly greater than the distance of the rear lockingend of the spring locking element 18 from the slot 22. Under these conditions, when the blade element 19 is inserted within the .clear space of. the sheath section 10, the spring locking element 18 will engageand slip above the lip 23'only when the blade element is pushed home. Any attempts to draw the two sections apart would only serve to cause the end of the locking element 18 to enter at greater length through the hole which lip23forms, The extent of this movement is limited and would amount to approximately the distance of shoulders 24, 24 from the slot 22 as illustrated in Fig, 1;

The under surface of the under lap 13 is intended to come into contact withthe flexible material .or paper of the envelope with which the safety-lock is to be used and this is another feature which is characteristic of the present invention. When the sheath section 10 is mounted in position all of theprongs 25, extending from the sheath section and provided for this purpose, are bent over to engage the paper and at the same time the under surface of the sheath section isffirmly pressed against the other side of the paper. The result of-this operation is that a tight fit exits between the sheath section and the paper with the effect that the relative expansibility or reaction of the paper below thespring locking element 18 (as illustrated at 26) tends to give further assistance in maintaining locking element 18 raised, thereby securing the locked relation with lip 23 when the sections are'together. In securing the sheath section to the paper, the paper may be scored, if desired, in

such a manner as to permit the lugs 16, 17, to

and. placed as to prevent any possible tampering with the safety-lock by attempting to get at the locking element from a position just above the surface of the paper.

In one aspect, the paper to which the sheath element is secured forms a backing forthis section, and this feature contributes to the production of a safety-lock which is made up of a minimum number of layers of sheet metal and is devoid of wasted space. A safety-lock having these assets is very desirable because of the space saved and the lessening of the number of probabilities of engagement with otherenvelopes, containers or mail matter. a The design of the blade 19 of the blade ele ment section 11 already has been disclosed.

The head 27 preferably has a rounded smooth contour 28 exposing no angular edges which could engage other articles. The three prongs 29 are triangularly placed and when they are turned over against the under surface of the paperthe edges 28 of the head are brought into close. contact with the paper. Prongs 30 contribute added strengthlto the fastenas faraway from the slot22as ispossible practically. The outwardly extending shoulders 24, 24further protect the approach to the slot 22.

lVhilethe form'of safety-lock herein shown I and described is admirably adapted to fulfill element, it will be remembered, isdisposed the objects primarily stated,it is to be under 2? stood that it is not intended to confine the V invention to the one form of embodiment herein disclosed, for it is susceptible of embodiment in various forms all coming within the scope of the claims which follow.

What I claim is 1. A safety-lock comprising a sheath section having an upper lap and an under lap connected together at one end, a spring locking element biased toward said upper lap, said upper lap and said under lap having adjacent surfaces which substantially contact each other except for an open central portion thereof wherein the upwardly biased spring locking element normally extends, said open central portion comprising a raised surface of one of said laps, and a blade ele- -ment adapted to enter within said open central portion of said sheath section and hav- 1' said rear end and being biased upwardly, and

a blade element adapted to enter between said upper lap and lower lap at the opening of said sheath section and having a locking lip adapted to be engaged by said spring locking element of said sheath section, said blade element having shoulders extending laterally from its longitudinal edges, and

spaced from the locking lip longitudinally of the blade element a distance substantially equal to the distance of the rear locking end i of said spring locking element from said opening. v

3. A safety-lock comprising a sheath sec-' tion having an upper lap and an under lap connected together at one edge, an open portion intermediate said two laps and communicating with an entrance close to another edge of said sheath member, means for maintaining the surfaces of said upper lap and lowerlap in substantial contacting relation near to the other two edges of said sheath section, a blade element adapted to enter at said entrance andto fit within said open por tion, a lip extending from the surface of said blade element, said lip being raised from the material of the blade element whereby a hole remains just forward of the lip, and a locking element extending from one of gaged by said locking element when said blade element is introduced into the sheath section and cause said locking element to further enter said hole when an attempt is made to withdraw the blade element from the sheath member.

4. A safety-lock comprising a sheath section having an upper lap and an under lap, said upper lap having a raised portion extending away from said under lap and forming a clear space, said under lap having a spring locking element biased toward said clear space, means for maintaining thecontacting surfaces of said upper lap and said lower lap in contacting relation, means extending over the under surfaces of said under lap and of a portion of said spring locking element for preventing said spring locking element from being displaced below the under surface of said under lap, and a blade element adapted to enter within said clear space, said blade element having a lip adapted to be engaged by said locking element whereby removal of the blade element is prevented.

In testimony whereof I hereto aflix my signature.

THEODORE B. LEWIS.

said laps and normally extending into said open vportion whereby said lip may be en- 

